It should have been a holiday in Hades: a ski resort with no snow. I had a family with poles, boots and goggles - and only grassy slopes where there should have been pistes. We had, of course, been chancing our luck, arriving in mid-April at a low-level resort for some hastily arranged late-season skiing. Nevertheless, my sense of rising panic at the sight of those green, shining hills was intense.

Yet we were saved from disaster for a simple reason: we had picked, by chance, a perfect spot to indulge in just about any other holiday activity you could care to think of. For this was Sundance - actor Robert Redford's Utah pleasure dome, arts institute, eco-experience and, occasionally, ski resort. In the end, it was to provide us with one of our finest family holidays.

Despite my visible angst, the receptionist merely smiled apologetically, directed us to lodgings and within a couple of hours had presented us with list of activities that were to keep us engrossed - and daunted - for the next five days. We made silver jewellery, shaped pots, hiked into the hills, peered round the houses of the rich and famous, ate spectacularly, bathed in hot springs, and wallowed luxuriously in the magical mountain atmosphere. Skiing, it transpires, is a very minor part of the Sundance experience.

Most things seem possible here, but the resort's real joy is its insight into the world of Redford, whose personality permeates every crevice of Sundance. He originally bought a two-acre plot here in 1961, when still an unknown actor, and built a house below the shimmering peak of Mount Timpanogos. Then, over the years, he acquired more and more land. 'I could hear the thundering hooves of development galloping towards it,' he recalled. He accumulated almost 25,000 acres: all of it is now protected territory. Within this prime Utah estate, Sundance - named after Redford's character in Butch Cassidy and the Sundance Kid - has evolved at its core, and now covers 6,000 acres of glistening forest and canyon.

As this development was going on, Redford's career was blossoming, but in the 1970s he made Downhill Racer as part of a planned trilogy on the American mythology of success. The film was marketed by Paramount as an action thriller and later dropped. Thus began Redford's grievance against the Hollywood studio system and in 1981, in the heart of his rustic paradise, he built the Sundance Institute as an independent movie makers' laboratory. Early beneficiaries included Quentin Tarantino, whose Reservoir Dogs was conceived here. The Sundance Festival emerged shortly afterwards. Steven Soderbergh showed his steamy, voyeuristic drama, Sex, Lies and Videotape, and The Blair Witch Project and the Coen Brothers' Blood Simple also had their first screenings. The festival, held in January, has become America's most important showcase for independent directors.

But both institute and festival are expensive, and studio money has always been unwelcome. To raise cash, Redford conceived the resort, and his catalogue of tasteful, eco-friendly goods - toiletries, food, and clothing that are sold in its general store and on the internet. The aim, he says, is to create a place that is 'lush and spare, sophisticated and primitive'. By and large he has succeeded, for Sundance is the antithesis of every other tourist resort I have been to in America, with not a burger bar or coffee franchise in sight. Moose, elks, chipmunks, blue jays and strange, gopher-like creatures called pot-guts wander around in summer. All in all, it is extraordinarily, almost obsessively, eco-friendly and tasteful.

Our condo was a stunning, split-level wooden affair that opened out on to woodland and had breathtaking vistas of the mountains. There were complimentary Aveda toiletries in every room, as well as Sundance's own range of soaps. On the walls were works of native art and old prints.

The old and weary - and rich - can pamper themselves at the resort's lavish spa, where highlights include the foot soak and the stone massage, which involves warmed basalt stones being placed on 'pressure points'. Even here you cannot escape the Sundance creed. The spa's wall insulation is made of recycled denim, and the walls themselves are constructed of compressed sunflower kernels.

When it comes to keeping summer weeds off ski slopes, herbicides are banned and a herd of goats is dispatched to graze there.

Other Redford obsessions include the Owl Bar's ancient rosewood counter, drinks cabinets and mirrored panels, which he discovered in an old biker's boozer in Thermopolis, Wyoming, a drinking hole that was allegedly frequented by the real Butch Cassidy. Redford bought the lot and moved them intact to Sundance where workers slaved for two years to remove pieces of shagpile, Formica and dubious stains. The ensemble now forms a glorious altar for the worship of alcohol, a particularly welcome feature in a state famed for its misanthropic attitude to drink.

Then there is the Tree Room, the resort's main restaurant. In the late Seventies Redford helped stop the construction of a nearby power plant and, as a token of local gratitude, a neighbour presented him with a family heirloom: a giant carpet woven in the 1800s by Ute Indians to commemorate a battle against US troopers. Pieces of blue coat, taken from dead cavalrymen, are woven into the tapestry, which covers a wall of the Tree Room and provided a rather unsettling back ground as we wolfed down our plates of venison in berry sauce and buffalo steaks in jus.

The combination of rustic luxury and strict environmentalism mixed with high living is certainly strange. We had a blow-out haute cuisine meal at the Tree Room one night and then sat outside watching local Native Americans drumming and chanting round a fire pit. Our eight year old, Livvy, was engrossed, though the rest of us found it strangely sad and voyeuristic.

On the other hand, there is no feeling of being trapped in an alternative universe, as there is at Disneyland or Center Parcs, and no gates or fencing to keep you and the rest of the world apart. My elder daughter Anna and I spent one day at nearby Park City (where the main Sundance Festival has now been transported) and actually managed some skiing. There were no queues, some surprisingly pleasant Alpine-style restaurants, and a lot of good runs. We also tried the local hot springs where the rusty tubs and old fencing contrasted sharply with the pristine conditions of Sundance.

The major hit for the kids was the jewellery-making at the Art Shack. Anna and Livvy made tasteful rings, bracelets and necklaces while Tom constructed a giant silver crossthat could have graced Ozzy Osbourne.

For my wife Sarah and I, the hike into the hills to the local waterfalls was the high point.

Bumping into Redford - who pops up regularly to keep an eye on affairs - would have trumped everything, but his absence didn't matter. After our time at Sundance I now have a good idea of what kind of man he is: careful, obsessive, meticulous and, to his credit, preoccupied with the world around him.

Factfile

Three nights in a Mountain Suite condominium for four people at Sundance (00 1 800 892 1600) costs $740. The package includes breakfast in the Foundry Grill, eight activity vouchers and two one-hour massages.

Fly-drive holidays to Salt Lake City with United Vacations (0870 606 2222), start at £650 per person, including taxes but excluding accommodation.